KR950009583B1 - Method and device to acknowledge collision of data in msx computer network - Google Patents

Abstract

The method for recognizing the collision by checking the state of the transmission line in an MSX computer network comprises the steps of inputting a busy number at a proper number register and setting the counter corresponding to two times of checking time; if the counter is set, judging whether there is a busy frame or not; if there is no busy frame, reducing the counter; if the counter is "0", outputting a checking frame by inputting its own number at the proper number register; if the checking frame is outputted, comparing the first, second and third data with its own number; and if the data is not its own number, setting the counter corresponding to two times of the checking time by delaying and if the data is its own number, transmitting the busy frame and thereafter the transmission frame.

Description

How to recognize collisions by checking the status of transmission line in MSX Computer Network

1 is a block diagram of the overall configuration according to the present invention.

2 is a configuration diagram of the MS computer network.

3 is a block diagram of a frame transmitted from the MS computer network.

4 is an exemplary view showing a data format of a transmission line that can be recognized by a communication processing apparatus having an independent unique number.

FIG. 5 is an exemplary view showing when a BUSY frame is first transmitted in front of a transmission frame in a manner of indicating that a transmission line is in use.

FIG. 6 is an exemplary view showing the definition of the time taken for transmitting a transmission frame when the maximum size of the “information” portion defined in FIG. 3 is limited.

7 is a flowchart of inspection of transmission line and transmission of transmission frame.

8 is an exemplary view showing a collision inspection frame.

* Explanation of symbols for main parts of the drawings

1: central processing unit 2: communication processing unit

3: ROM 4: RAM

5: data selector 6: unique number latch

8: line driver 9: line receiver

10, 11: modular jack 12: transmission line

13: clock supply circuit 14: reset circuit

The present invention relates to a method and apparatus for recognizing a collision by inspecting a state of a data transmission line between each MSX computer, in particular in a network composed of MSX computers.

Each MS computer on the MS network where communication processing devices are connected by a bus structure determines whether data is transmitted or not on the transmission line when data is transmitted through the transmission line only when no data is transmitted. Should be able to send and receive

For this purpose, transmission line sensing circuits are generally used, but the sensing circuits are expensive and are not suitable for use in general 8-bit computers.

SUMMARY OF THE INVENTION The present invention has been made in view of this point, and provides a method and apparatus for avoiding collision between data transmitted on a transmission line by examining a state of the transmission line by a predetermined program without having a separate transmission line detection circuit. There is an object of the present invention.

This will be described with reference to the accompanying drawings.

7 is a flowchart of the inspection of the transmission line and the transmission of the transmission frame. When the inspection of the transmission line starts, the process of setting a counter corresponding to twice the inspection time T by writing a busy number in the unique number register; If the counter is set, the process of determining the presence or absence of busy frame, and if the busy frame is determined, if there is no busy frame, the process of determining the counter by reducing the counter, and if the counter is determined to be "0" The process of sending a test frame by rewriting its own unique number into the jister, and the process of comparing and determining the first, second, and third data and its own unique number when the test frame is sent, and the uniqueness of the comparison judged If it is not a number, it sets the counter corresponding to 2 times of T and if it is its own number, it sends a busy frame and sends a transmission frame. Provides a way.

1 is an overall block diagram according to the present invention, which includes a central processing unit (1) for controlling the entire system, a communication processing unit (2) that is responsible for transmitting and receiving a network, and data presence or absence of data on the transmission line (12). ROM 3 having an algorithm for discriminating and preventing collision between data during transmission and RAM 4 and central processing unit 1 storing data temporarily are ROM 3 RAM 4 communication processing apparatus 2 And a data selector 5 for selecting and selecting a unique number latch 6, a unique number latch 6 which may have 32 unique numbers, and a unique number set in the unique number latch 6; The apparatus of the invention by interconnecting a switch (7), a line driver (8), a line receiver (9), a modular pack (10), (11) a transmission line (12), a clock supply circuit (13) and a reset circuit (14) Configure

Hereinafter, the operation and effects of the present invention will be described with reference to the accompanying drawings.

If the mode of the communication processing device 2 is set to SDLC and the address search mode is selected, a frame of data having the format shown in FIG. 3 can be sent, and the destination address of the frame is set to the communication processing device ( In the case of its own serial number written in the register in 2), it is possible to receive a frame of data having the format shown in FIG.

In addition, the data transfer rate can be programmed into a register in the communication processing apparatus 2, and accordingly, the clock and the value supplied to the communication processing apparatus 2 have the following communication rates.

×클럭주파수(초당전송비트수)…………식(1)Communication speed

Clock frequency (transmit bits per second) … … … Formula (1)

On the other hand, since the communication processing apparatus 2 can recognize only the frame shown in FIG. 3 having only the destination address identical to its own unique number on the transmission line 12, it cannot detect that information is transmitted to and from another network device. It is understood that there is data to be transmitted on the transmission line 12 only when a signal such as that of FIG. 4 appears on the transmission line 12. The network device that can participate in the network is the line driver of FIG. It is limited to 32 by the characteristics of (8).

However, each network device determines the maximum size of the information portion shown in FIG. 3, and assigns a busy frame having a busy number, which is not used in the network in front of each transport frame, on the transmission line 12 as shown in FIG. Each communication processing device can recognize the busy frame.

Therefore, after writing the number of busy frames previously promised in the register of the communication processing apparatus 2 in which its own number is inputted, the busy frames have been made for twice as long as the inspection period "T" shown in FIG. If busy frame appears, if the busy frame appears, double check the inspection period "T" again according to the flowchart shown in FIG. 7 to check whether the busy frame appears for two times the inspection period "T". If the frame does not appear, it means that there is no data transmitted through the transmission line 12. Therefore, a test frame as shown in FIG. 8 is sent out on the transmission line 12, and if the other network of the frame interferes, that is, by simultaneous transmission. Check for collisions with other data.

That is, the three-byte unique number is sent out on the transmission line 12 in turn, and receives and stores the information on the transmission line 12, and transmits all three-byte inspection frames, and then receives the information from the transmission line 12. Checks whether it matches its own serial number.

This means that data can be sent and received through the transmission line 12 that matched its own number. If the data is not matched by starting data transmission, the busy frame is checked again according to the flowchart of FIG. 7 after an appropriate time elapses. Starting with and repeating the above process until it receives the information corresponding to the unique number sent by itself, it is determined whether the transmission line 12 can be used before the data is transmitted.

As described above, according to the present invention, in a network composed of MS computers, data collision between data transmissions between computers on the transmission line 12 can be prevented when data is transmitted between MS computers. It is advantageous in that data can be accurately transmitted to an MS computer on a desired network without having a transmission line sensing circuit.

Claims (2)

When the transmission line test is started, writing a busy number in the unique number register to set a counter corresponding to twice the test time T; and when the counter is set, determining whether or not a busy frame is present; Busy frame, whether or not busy frame is determined, if there is no busy frame, the counter is decremented to determine the counter, and if the counter is determined to be "0", the process of sending a check frame by rewriting its own number in the unique number register. And, when the check frame is sent out the process of comparing and determining the first, second, third data and its own unique number, and if the comparison is not its own unique number is determined by setting a counter corresponding to twice the T and If it is its own number, it checks the status of the transmission line in MS X computer network which is composed of sending busy frame and sending transmission frame. How to recognize a conflict. In a network in which an MS computer is configured by using a communication processor (2) including a line driver (8), a radio receiver (9), a modular jack (10), and a transmission line (12), a clock supply circuit (13) And a reset circuit 14 connected to the central processing unit 1 for controlling the entire system, and a ROM having an algorithm for discriminating data presence or absence of the transmission line 12 and preventing collision between data transmissions. 3), RAM (4) for temporarily storing data, and the central processing unit (1) to select and select the ROM (3) RAM (4) communication processing unit (2) and unique number latch (6) MS, characterized in that it comprises a data selector (5), a unique code latch 6 that can have 32 unique numbers, and a switch 7 for setting a unique number in the unique number latch (6) A device that detects collisions by examining the status of a transport layer on a computer network.

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